Compound and natural key

Question

Explain the alternate, partial, artificial, compound and natural key.

Answer 1

It refers to a set of attributes which uniquely recognize the weak entities and which are related to the same owner entity. It is sometime known as the Discriminator.

Alternate Key:

All the Candidate Keys excluding Primary Key are termed as the Alternate Keys.

Artificial Key:

If no obvious key either stands alone or compound is available, then last resort is to simply form a key, by allocating a unique number to every record or the occurrence. Then this is termed as developing an artificial key.

Compound Key:

If no single data element uniquely recognizes occurrences within a construct, then joining the multiple components to develop a unique identifier for construct is called as developing a compound key.

Natural Key:

When one of the data components stored within the construct is used as the primary key, then it is known as the natural key.